drivers/cpuidle/cpuidle.c

   1 /*
   2  * cpuidle.c - core cpuidle infrastructure
   3  *
   4  * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
   5  *               Shaohua Li <shaohua.li@intel.com>
   6  *               Adam Belay <abelay@novell.com>
   7  *
   8  * This code is licenced under the GPL.
   9  */
  10
  11 #include <linux/clockchips.h>
  12 #include <linux/kernel.h>
  13 #include <linux/mutex.h>
  14 #include <linux/sched.h>
  15 #include <linux/notifier.h>
  16 #include <linux/pm_qos.h>
  17 #include <linux/cpu.h>
  18 #include <linux/cpuidle.h>
  19 #include <linux/ktime.h>
  20 #include <linux/hrtimer.h>
  21 #include <linux/module.h>
  22 #include <trace/events/power.h>
  23
  24 #include "cpuidle.h"
  25
  26 DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
  27 DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
  28
  29 DEFINE_MUTEX(cpuidle_lock);
  30 LIST_HEAD(cpuidle_detected_devices);
  31
  32 static int enabled_devices;
  33 static int off __read_mostly;
  34 static int initialized __read_mostly;
  35 static bool use_deepest_state __read_mostly;
  36
  37 int cpuidle_disabled(void)
  38 {
  39         return off;
  40 }
  41 void disable_cpuidle(void)
  42 {
  43         off = 1;
  44 }
  45
  46 /**
  47  * cpuidle_play_dead - cpu off-lining
  48  *
  49  * Returns in case of an error or no driver
  50  */
  51 int cpuidle_play_dead(void)
  52 {
  53         struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
  54         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
  55         int i;
  56
  57         if (!drv)
  58                 return -ENODEV;
  59
  60         /* Find lowest-power state that supports long-term idle */
  61         for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
  62                 if (drv->states[i].enter_dead)
  63                         return drv->states[i].enter_dead(dev, i);
  64
  65         return -ENODEV;
  66 }
  67
  68 /**
  69  * cpuidle_use_deepest_state - Enable/disable the "deepest idle" mode.
  70  * @enable: Whether enable or disable the feature.
  71  *
  72  * If the "deepest idle" mode is enabled, cpuidle will ignore the governor and
  73  * always use the state with the greatest exit latency (out of the states that
  74  * are not disabled).
  75  *
  76  * This function can only be called after cpuidle_pause() to avoid races.
  77  */
  78 void cpuidle_use_deepest_state(bool enable)
  79 {
  80         use_deepest_state = enable;
  81 }
  82
  83 /**
  84  * cpuidle_find_deepest_state - Find the state of the greatest exit latency.
  85  * @drv: cpuidle driver for a given CPU.
  86  * @dev: cpuidle device for a given CPU.
  87  */
  88 static int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
  89                                       struct cpuidle_device *dev)
  90 {
  91         unsigned int latency_req = 0;
  92         int i, ret = CPUIDLE_DRIVER_STATE_START - 1;
  93
  94         for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
  95                 struct cpuidle_state *s = &drv->states[i];
  96                 struct cpuidle_state_usage *su = &dev->states_usage[i];
  97
  98                 if (s->disabled || su->disable || s->exit_latency <= latency_req)
  99                         continue;
 100
 101                 latency_req = s->exit_latency;
 102                 ret = i;
 103         }
 104         return ret;
 105 }
 106
 107 /**
 108  * cpuidle_enter_state - enter the state and update stats
 109  * @dev: cpuidle device for this cpu
 110  * @drv: cpuidle driver for this cpu
 111  * @next_state: index into drv->states of the state to enter
 112  */
 113 int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
 114                         int index)
 115 {
 116         int entered_state;
 117
 118         struct cpuidle_state *target_state = &drv->states[index];
 119         ktime_t time_start, time_end;
 120         s64 diff;
 121
 122         time_start = ktime_get();
 123
 124         entered_state = target_state->enter(dev, drv, index);
 125
 126         time_end = ktime_get();
 127
 128         if (!cpuidle_state_is_coupled(dev, drv, entered_state))
 129                 local_irq_enable();
 130
 131         diff = ktime_to_us(ktime_sub(time_end, time_start));
 132         if (diff > INT_MAX)
 133                 diff = INT_MAX;
 134
 135         dev->last_residency = (int) diff;
 136
 137         if (entered_state >= 0) {
 138                 /* Update cpuidle counters */
 139                 /* This can be moved to within driver enter routine
 140                  * but that results in multiple copies of same code.
 141                  */
 142                 dev->states_usage[entered_state].time += dev->last_residency;
 143                 dev->states_usage[entered_state].usage++;
 144         } else {
 145                 dev->last_residency = 0;
 146         }
 147
 148         return entered_state;
 149 }
 150
 151 /**
 152  * cpuidle_select - ask the cpuidle framework to choose an idle state
 153  *
 154  * @drv: the cpuidle driver
 155  * @dev: the cpuidle device
 156  *
 157  * Returns the index of the idle state.
 158  */
 159 int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 160 {
 161         if (off || !initialized)
 162                 return -ENODEV;
 163
 164         if (!drv || !dev || !dev->enabled)
 165                 return -EBUSY;
 166
 167         if (unlikely(use_deepest_state))
 168                 return cpuidle_find_deepest_state(drv, dev);
 169
 170         return cpuidle_curr_governor->select(drv, dev);
 171 }
 172
 173 /**
 174  * cpuidle_enter - enter into the specified idle state
 175  *
 176  * @drv:   the cpuidle driver tied with the cpu
 177  * @dev:   the cpuidle device
 178  * @index: the index in the idle state table
 179  *
 180  * Returns the index in the idle state, < 0 in case of error.
 181  * The error code depends on the backend driver
 182  */
 183 int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 184                   int index)
 185 {
 186         if (cpuidle_state_is_coupled(dev, drv, index))
 187                 return cpuidle_enter_state_coupled(dev, drv, index);
 188         return cpuidle_enter_state(dev, drv, index);
 189 }
 190
 191 /**
 192  * cpuidle_reflect - tell the underlying governor what was the state
 193  * we were in
 194  *
 195  * @dev  : the cpuidle device
 196  * @index: the index in the idle state table
 197  *
 198  */
 199 void cpuidle_reflect(struct cpuidle_device *dev, int index)
 200 {
 201         if (cpuidle_curr_governor->reflect && !unlikely(use_deepest_state))
 202                 cpuidle_curr_governor->reflect(dev, index);
 203 }
 204
 205 /**
 206  * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
 207  */
 208 void cpuidle_install_idle_handler(void)
 209 {
 210         if (enabled_devices) {
 211                 /* Make sure all changes finished before we switch to new idle */
 212                 smp_wmb();
 213                 initialized = 1;
 214         }
 215 }
 216
 217 /**
 218  * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
 219  */
 220 void cpuidle_uninstall_idle_handler(void)
 221 {
 222         if (enabled_devices) {
 223                 initialized = 0;
 224                 kick_all_cpus_sync();
 225         }
 226 }
 227
 228 /**
 229  * cpuidle_pause_and_lock - temporarily disables CPUIDLE
 230  */
 231 void cpuidle_pause_and_lock(void)
 232 {
 233         mutex_lock(&cpuidle_lock);
 234         cpuidle_uninstall_idle_handler();
 235 }
 236
 237 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
 238
 239 /**
 240  * cpuidle_resume_and_unlock - resumes CPUIDLE operation
 241  */
 242 void cpuidle_resume_and_unlock(void)
 243 {
 244         cpuidle_install_idle_handler();
 245         mutex_unlock(&cpuidle_lock);
 246 }
 247
 248 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
 249
 250 /* Currently used in suspend/resume path to suspend cpuidle */
 251 void cpuidle_pause(void)
 252 {
 253         mutex_lock(&cpuidle_lock);
 254         cpuidle_uninstall_idle_handler();
 255         mutex_unlock(&cpuidle_lock);
 256 }
 257
 258 /* Currently used in suspend/resume path to resume cpuidle */
 259 void cpuidle_resume(void)
 260 {
 261         mutex_lock(&cpuidle_lock);
 262         cpuidle_install_idle_handler();
 263         mutex_unlock(&cpuidle_lock);
 264 }
 265
 266 /**
 267  * cpuidle_enable_device - enables idle PM for a CPU
 268  * @dev: the CPU
 269  *
 270  * This function must be called between cpuidle_pause_and_lock and
 271  * cpuidle_resume_and_unlock when used externally.
 272  */
 273 int cpuidle_enable_device(struct cpuidle_device *dev)
 274 {
 275         int ret;
 276         struct cpuidle_driver *drv;
 277
 278         if (!dev)
 279                 return -EINVAL;
 280
 281         if (dev->enabled)
 282                 return 0;
 283
 284         drv = cpuidle_get_cpu_driver(dev);
 285
 286         if (!drv || !cpuidle_curr_governor)
 287                 return -EIO;
 288
 289         if (!dev->registered)
 290                 return -EINVAL;
 291
 292         if (!dev->state_count)
 293                 dev->state_count = drv->state_count;
 294
 295         ret = cpuidle_add_device_sysfs(dev);
 296         if (ret)
 297                 return ret;
 298
 299         if (cpuidle_curr_governor->enable &&
 300             (ret = cpuidle_curr_governor->enable(drv, dev)))
 301                 goto fail_sysfs;
 302
 303         smp_wmb();
 304
 305         dev->enabled = 1;
 306
 307         enabled_devices++;
 308         return 0;
 309
 310 fail_sysfs:
 311         cpuidle_remove_device_sysfs(dev);
 312
 313         return ret;
 314 }
 315
 316 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
 317
 318 /**
 319  * cpuidle_disable_device - disables idle PM for a CPU
 320  * @dev: the CPU
 321  *
 322  * This function must be called between cpuidle_pause_and_lock and
 323  * cpuidle_resume_and_unlock when used externally.
 324  */
 325 void cpuidle_disable_device(struct cpuidle_device *dev)
 326 {
 327         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 328
 329         if (!dev || !dev->enabled)
 330                 return;
 331
 332         if (!drv || !cpuidle_curr_governor)
 333                 return;
 334
 335         dev->enabled = 0;
 336
 337         if (cpuidle_curr_governor->disable)
 338                 cpuidle_curr_governor->disable(drv, dev);
 339
 340         cpuidle_remove_device_sysfs(dev);
 341         enabled_devices--;
 342 }
 343
 344 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
 345
 346 static void __cpuidle_unregister_device(struct cpuidle_device *dev)
 347 {
 348         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 349
 350         list_del(&dev->device_list);
 351         per_cpu(cpuidle_devices, dev->cpu) = NULL;
 352         module_put(drv->owner);
 353 }
 354
 355 static void __cpuidle_device_init(struct cpuidle_device *dev)
 356 {
 357         memset(dev->states_usage, 0, sizeof(dev->states_usage));
 358         dev->last_residency = 0;
 359 }
 360
 361 /**
 362  * __cpuidle_register_device - internal register function called before register
 363  * and enable routines
 364  * @dev: the cpu
 365  *
 366  * cpuidle_lock mutex must be held before this is called
 367  */
 368 static int __cpuidle_register_device(struct cpuidle_device *dev)
 369 {
 370         int ret;
 371         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 372
 373         if (!try_module_get(drv->owner))
 374                 return -EINVAL;
 375
 376         per_cpu(cpuidle_devices, dev->cpu) = dev;
 377         list_add(&dev->device_list, &cpuidle_detected_devices);
 378
 379         ret = cpuidle_coupled_register_device(dev);
 380         if (ret)
 381                 __cpuidle_unregister_device(dev);
 382         else
 383                 dev->registered = 1;
 384
 385         return ret;
 386 }
 387
 388 /**
 389  * cpuidle_register_device - registers a CPU's idle PM feature
 390  * @dev: the cpu
 391  */
 392 int cpuidle_register_device(struct cpuidle_device *dev)
 393 {
 394         int ret = -EBUSY;
 395
 396         if (!dev)
 397                 return -EINVAL;
 398
 399         mutex_lock(&cpuidle_lock);
 400
 401         if (dev->registered)
 402                 goto out_unlock;
 403
 404         __cpuidle_device_init(dev);
 405
 406         ret = __cpuidle_register_device(dev);
 407         if (ret)
 408                 goto out_unlock;
 409
 410         ret = cpuidle_add_sysfs(dev);
 411         if (ret)
 412                 goto out_unregister;
 413
 414         ret = cpuidle_enable_device(dev);
 415         if (ret)
 416                 goto out_sysfs;
 417
 418         cpuidle_install_idle_handler();
 419
 420 out_unlock:
 421         mutex_unlock(&cpuidle_lock);
 422
 423         return ret;
 424
 425 out_sysfs:
 426         cpuidle_remove_sysfs(dev);
 427 out_unregister:
 428         __cpuidle_unregister_device(dev);
 429         goto out_unlock;
 430 }
 431
 432 EXPORT_SYMBOL_GPL(cpuidle_register_device);
 433
 434 /**
 435  * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 436  * @dev: the cpu
 437  */
 438 void cpuidle_unregister_device(struct cpuidle_device *dev)
 439 {
 440         if (!dev || dev->registered == 0)
 441                 return;
 442
 443         cpuidle_pause_and_lock();
 444
 445         cpuidle_disable_device(dev);
 446
 447         cpuidle_remove_sysfs(dev);
 448
 449         __cpuidle_unregister_device(dev);
 450
 451         cpuidle_coupled_unregister_device(dev);
 452
 453         cpuidle_resume_and_unlock();
 454 }
 455
 456 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
 457
 458 /**
 459  * cpuidle_unregister: unregister a driver and the devices. This function
 460  * can be used only if the driver has been previously registered through
 461  * the cpuidle_register function.
 462  *
 463  * @drv: a valid pointer to a struct cpuidle_driver
 464  */
 465 void cpuidle_unregister(struct cpuidle_driver *drv)
 466 {
 467         int cpu;
 468         struct cpuidle_device *device;
 469
 470         for_each_cpu(cpu, drv->cpumask) {
 471                 device = &per_cpu(cpuidle_dev, cpu);
 472                 cpuidle_unregister_device(device);
 473         }
 474
 475         cpuidle_unregister_driver(drv);
 476 }
 477 EXPORT_SYMBOL_GPL(cpuidle_unregister);
 478
 479 /**
 480  * cpuidle_register: registers the driver and the cpu devices with the
 481  * coupled_cpus passed as parameter. This function is used for all common
 482  * initialization pattern there are in the arch specific drivers. The
 483  * devices is globally defined in this file.
 484  *
 485  * @drv         : a valid pointer to a struct cpuidle_driver
 486  * @coupled_cpus: a cpumask for the coupled states
 487  *
 488  * Returns 0 on success, < 0 otherwise
 489  */
 490 int cpuidle_register(struct cpuidle_driver *drv,
 491                      const struct cpumask *const coupled_cpus)
 492 {
 493         int ret, cpu;
 494         struct cpuidle_device *device;
 495
 496         ret = cpuidle_register_driver(drv);
 497         if (ret) {
 498                 pr_err("failed to register cpuidle driver\n");
 499                 return ret;
 500         }
 501
 502         for_each_cpu(cpu, drv->cpumask) {
 503                 device = &per_cpu(cpuidle_dev, cpu);
 504                 device->cpu = cpu;
 505
 506 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
 507                 /*
 508                  * On multiplatform for ARM, the coupled idle states could be
 509                  * enabled in the kernel even if the cpuidle driver does not
 510                  * use it. Note, coupled_cpus is a struct copy.
 511                  */
 512                 if (coupled_cpus)
 513                         device->coupled_cpus = *coupled_cpus;
 514 #endif
 515                 ret = cpuidle_register_device(device);
 516                 if (!ret)
 517                         continue;
 518
 519                 pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
 520
 521                 cpuidle_unregister(drv);
 522                 break;
 523         }
 524
 525         return ret;
 526 }
 527 EXPORT_SYMBOL_GPL(cpuidle_register);
 528
 529 #ifdef CONFIG_SMP
 530
 531 static void smp_callback(void *v)
 532 {
 533         /* we already woke the CPU up, nothing more to do */
 534 }
 535
 536 /*
 537  * This function gets called when a part of the kernel has a new latency
 538  * requirement.  This means we need to get all processors out of their C-state,
 539  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
 540  * wakes them all right up.
 541  */
 542 static int cpuidle_latency_notify(struct notifier_block *b,
 543                 unsigned long l, void *v)
 544 {
 545         smp_call_function(smp_callback, NULL, 1);
 546         return NOTIFY_OK;
 547 }
 548
 549 static struct notifier_block cpuidle_latency_notifier = {
 550         .notifier_call = cpuidle_latency_notify,
 551 };
 552
 553 static inline void latency_notifier_init(struct notifier_block *n)
 554 {
 555         pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
 556 }
 557
 558 #else /* CONFIG_SMP */
 559
 560 #define latency_notifier_init(x) do { } while (0)
 561
 562 #endif /* CONFIG_SMP */
 563
 564 /**
 565  * cpuidle_init - core initializer
 566  */
 567 static int __init cpuidle_init(void)
 568 {
 569         int ret;
 570
 571         if (cpuidle_disabled())
 572                 return -ENODEV;
 573
 574         ret = cpuidle_add_interface(cpu_subsys.dev_root);
 575         if (ret)
 576                 return ret;
 577
 578         latency_notifier_init(&cpuidle_latency_notifier);
 579
 580         return 0;
 581 }
 582
 583 module_param(off, int, 0444);
 584 core_initcall(cpuidle_init);